Directing a power signal from a port power controller to one of multiple physical ports

ABSTRACT

A technique is able to direct a power signal from a port power controller to one of multiple physical ports. The technique involves activating a set of port power controllers. Each port power controller is constructed and arranged to deliver power to a device through at most one physical port at a time. The technique further involves performing a set of discovery operations to discover device presence, the set of discovery operations providing discovery data. The technique further involves providing, based on the discovery data provided by the set of discovery operations, a set of switching signals to switching circuitry which is coupled to a set of physical ports. The switching circuitry is constructed and arranged to steer power signals from the activated set of port power controllers through the set of physical ports to deliver power to a set of devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a Continuation of U.S. patent applicationSer. No. 13/047,417 filed on Mar. 14, 2011, entitled, “DISCOVERING ADEVICE PRESENCE AND DIRECTING A POWER SIGNAL TO THE DEVICE FROM A PORTPOWER CONTROLLER THROUGH AT MOST ONE OF MULTIPLE PHYSICAL PORTS AT ATIME”, the contents and teachings of which are hereby incorporated byreference in their entirety.

BACKGROUND

A conventional Power over Ethernet (PoE) system includes power sourcingequipment (PSE) and one or more powered devices (PDs) that connect tothe PSE through cabling (e.g., CAT5, CAT5e, CAT6, etc.). IEEE802.3af-2003 is a standard for delivering up to 12.95 Watts to a PD.IEEE 802.3at-2009 is a standard for delivering up to 25.5 Watts of powerto a PD.

Before the PSE delivers any power to a PD through one of its ports, thePSE typically performs a discovery operation through that port. Forexample, if the PSE does not detect a particular impedance whichidentifies the PD as a device which can receive power through that port,the PSE does not deliver power through that port thus preventing damageto the device. However, if the PSE detects the particular impedancethrough that port, the PSE delivers power to the PD through that port.IEEE 802.3af-2003 (PoE) and IEEE 802.3at-2009 (PoE Enhancements) provideadditional detection and classification details.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages will beapparent from the following description of particular embodiments of theinvention, as illustrated in the accompanying drawings in which likereference characters refer to the same parts throughout the differentviews. The drawings are not necessarily to scale, emphasis instead beingplaced upon illustrating the principles of various embodiments of theinvention.

FIG. 1 is a block diagram of an electronic environment which involvesdirecting a power signal from a port power controller to one of multiplephysical ports.

FIG. 2 is a block diagram of particular details of a PSE device of FIG.1.

FIG. 3 is a block diagram of a first power delivery topology for theelectronic environment of FIG. 1.

FIG. 4 is a block diagram of a second power delivery topology for theelectronic environment of FIG. 1.

FIG. 5 is a block diagram of a third power delivery topology for theelectronic environment of FIG. 1.

FIG. 6 is a flowchart of a procedure which is performed by controlcircuitry of the PSE device of FIG. 1.

DETAILED DESCRIPTION Overview

An improved technique involves directing a power signal from a portpower controller (e.g., a PSE controller) to one of multiple physicalports (e.g., RJ45 ports) through switching circuitry. Such a techniqueis capable of providing a PSE with significant power deliveryflexibility without the need to over provision the PSE with an excessivenumber port power controllers. In particular, suppose that each portpower controller of a PSE device is capable of providing up to apredefined amount of power (e.g., 30 Watts) to an external devicethrough a physical port. Further suppose that the external device isable to draw more than the predefined amount of power (e.g., theexternal device indicates to the PSE that the PSE should provide morethan 30 Watts). In this situation, the switching circuitry is able tosteer power from multiple port power controllers of the PSE to theexternal device through the same physical port to accommodate the powerneeds of the external device. Such a technique alleviates the need toprovision each physical port of the PSE device with multiple dedicatedport power controllers (i.e., multiple port power controllers which areexclusively dedicated to that physical port).

One embodiment is directed to a method which includes activating a setof port power controllers. Each port power controller is constructed andarranged to deliver power to a device through at most one physical portat a time. The method further includes performing a set of discoveryoperations to discover device presence, the set of discovery operationsproviding discovery data. The method further includes providing, basedon the discovery data provided by the set of discovery operations, a setof switching signals to switching circuitry which is coupled to the setof physical ports. The switching circuitry is constructed and arrangedto direct power signals from the activated set of port power controllersthrough the set of physical ports to deliver power to a set of devices.Such a method is thus able to steer a power signal from a port powercontroller (e.g., a PSE controller) to one of multiple physical ports.

Other embodiments are directed to an apparatus and a system for steeringa power signal from a port power controller to one of multiple physicalports. Yet other embodiments are directed to logic (e.g., a computerprogram product, logic circuitry, etc.) for steering a power signal froma port power controller to one of multiple physical ports, and so on.

Description of Example Embodiments

FIG. 1 shows an electronic environment 20 having a PSE device 22,external devices 24(A), 24(B), . . . (collectively, external devices 24)and cabling 26(A), 26(B), . . . (collectively, cabling 26). The externaldevices 24 may include PDs as well as devices which are not able toaccept inline power. Advantageously, the PSE device 22 is equipped withelectronic circuitry which enables steering of a power signal from aport power controller to different physical ports for flexible inlinepower delivery.

As shown in FIG. 1, the PSE device 22 includes data communicationscircuitry 30, power delivery circuitry 32 (illustrated generally by thearrow 32), and physical ports 34(A), 34(B), . . . (collectively,physical ports 34). The data communications circuitry 30 is constructedand arranged to perform data communications operations and exchange datasignals 40(TX), 40(RX) (collectively, data signals 40) with the externaldevices 24 through the physical ports 34. The power delivery circuitry32 is constructed and arranged to identify the presence of PDs among theexternal devices 24, and to deliver inline power signals 42appropriately to the PDs through the physical ports 34 (e.g., 15 Watts,30 Watts, greater than 30 Watts, etc.).

The power delivery circuitry 32 includes a power supply 50, port powercontrollers 52(1), 52(2), . . . (collectively, port power controllers52), power signal switches 54(1)(A), 54(1)(B), 54(2)(A), 54(2)(B), . . .(collectively, power signal switches 54), and power signal steeringcircuitry 56. Preferably, the power supply 50 has enough capacity topower the operation of multiple PDs through multiple physical ports 34as well as power the PSE device 22 itself.

Each port power controller 52 couples to multiple power signal switches54 leading to multiple physical ports 34. For example, the port powercontroller 52(1) couples to power signal switches 54(1)(A) and 54(1)(B)which lead to physical ports 34(A) and 34(B), respectively. Similarly,the port power controller 52(2) couples to power signal switches54(2)(A) and 54(2)(B) which lead to physical ports 34(A) and 34(B),respectively. In some arrangements, the power signal switches 54 arediscrete transistors which are capable of handling relatively largeamounts of current (e.g., MOSFETs).

The power signal switches 54 form an array of switches 54 which steerspower signals 42 from different port power controllers 52 to differentphysical ports 34. That is, such a switch arrangement enables directionof a power signal 42 from each port power controller 52 to one ofmultiple physical ports 34 in the manner of a de-multiplexer.Furthermore, such a switch arrangement enables each physical port 34 toreceive power signals 42 from multiple port power controllers 52,perhaps simultaneously if delivering inline power to a high power PD.

It should be understood that each port power controller 52 is shown inFIG. 1 as coupling to two power signal switches 54 respectively leadingto two physical ports 34 by way of example and for simplicity. However,as illustrated by the ellipses (“ . . . ”) in FIG. 1, each port powercontroller 52 may couple to more than two power signal switches 54leading to more than two physical ports 34. In some arrangements, thearray of switches 54 is constructed and arranged to provide 1-to-anyconnectivity to any physical port 34 of the PSE device 22.

It should be further understood that, upon activation, the power signalsteering circuitry 56 obtains a set of PD discovery signals 60 and theport power controllers 52 are capable of running in a variety ofoperating modes. For example, in discovery mode, the port powercontrollers 52 do not provide inline power but periodically sense forcharacteristic impedance which indicates the presence of PDs. In someembodiments, the power signal steering circuitry 56 is pre-configured toprovide a set of switch signals 62 to the power signal switches 54 toinitially connect each port power controller 52 to a respective physicalport 34.

Once a port power controller 52 connects to a respective physical port34, the port power controller 52 performs inline power discoveryoperations (e.g., PD detection and classification). If the port powercontroller 52 discovers a PD in need of inline power, the port powercontroller 52 delivers inline power to that PD. However, if the portpower controller 52 does not discover a PD in need of inline power, thepower signal steering circuitry 56 can decide to connect the port powercontroller 52 a different physical port 34 to discover a PD which mayneed inline power.

As shown in FIG. 1, one will appreciate that the port power controller52(1) is capable of performing PD discovery and power up operations withthe external device 24(A) through the power signal switch 54(1)(A) andthe physical port 34(A). Likewise, the port power controller 52(2)performs PD discovery and power up operations with the external device24(B) through the power signal switch 54(2)(B) and the physical port34(B), and so on.

Since there are alternative pathways available, it is further possiblefor the port power controllers 52 to perform PD discovery and power upoperations through other power signal switches 54 as well. For example,the port power controller 52(1) is capable of performing PD discoveryand power up operations with the external device 24(B) through the powersignal switch 54(1)(B) and the physical port 34(B). Similarly, the portpower controller 52(2) is capable of performing PD discovery and powerup operations with the external device 24(A) through the power signalswitch 54(2)(A) and the physical port 34(A), and so on.

Once the port power controllers 52 have completed inline power discoveryoperations with the external devices 24, the port power controllers 52pass the results of the inline PD discovery operations to the powersignal steering circuitry 56 via PD discovery signals 60. It should beunderstood that, due to the switching operation of the power signalsteering circuitry 56, each port power controller 52 attaches to onlyone physical port 34 at a time.

Additionally, the power signal steering circuitry 56 is capable ofproviding feedback and control signals 64 to the port power controllers52. Such signals 64 enable, among other things, the port powercontrollers 52 to coordinate their operation among each other. Forexample, in response to a power negotiation operation resulting indiscovery of a high power PD, the power signal steering circuitry 56able to coordinate delivery of inline power from multiple port powercontrollers 52 through the same physical port 34, i.e., delivery of upto 60 Watts from two port power controllers 52 to a PD through aphysical port 34.

It should be understood that the port power controllers 52 are capableof routinely re-performing the inline power negotiation operations withthe external devices 24, and then updating the PD discovery signals 60provided to the power signal steering circuitry 56. For example, whilein discovery mode, the port power controllers 52 can periodically sensefor new PDs on physical ports 34 which originally did not connect toPDs.

Additionally, while in inline power mode, the port power controllers 52can periodically renegotiate power delivery with existing PDs inresponse to certain events (e.g., based on a time schedule, a change inpower demand, periodically, etc.). As a result of the activity of thepower signal steering circuitry 56, the power signal steering circuitry56 may maintain the switch signals 62 at existing settings to maintainthe power delivery configuration of the PSE device 22, or alter theswitch signals 62 from the existing settings to re-distribute the powersignals 42 to among the external devices 24. Furthermore, via thefeedback and control signals 64, the power signal steering circuitry 56can coordinate operation of the port power controllers 52 in an ongoingmanner.

In some arrangements, each port power controller 52 performs PDdiscovery during a discovery phase, and PD classification during aclassification phase through at least one physical port 34. Furthermore,when a port power controller 52 delivers inline power through a physicalport 34, the port power controller 52 preferably regulates andconditions its power signal 42 for proper delivery of power to the PD.The particular operation of each port power controller 52 may be definedby one or more PoE standards including IEEE 802.3af-2003 and IEEE802.3at-2009.

Additionally, transceivers of the data communications circuitry 32exchange transmit signals 40(TX) and receive signals 40(RX) with theexternal devices 24 through the physical ports 34. In some arrangements,networking circuitry of the data communications circuitry 32 operates asnetwork node (e.g., a router, a network switch, etc.). In otherarrangements, the networking circuitry of the data communicationscircuitry 32 operates as an endpoint device (e.g., a Voice over IPsystem manager, a closed-circuit television server, etc.).

Furthermore, the wiring pathways for the cabling 26 preferably includeseight copper conductors arranged as four twisted wire pairs for two-pairinline power delivery (e.g., up to 30 Watts) or four-pair inline powerdelivery (e.g., up to 60 Watts). Suitable wiring for the cable 26includes (e.g., CAT5, CAT5e, CAT6, and the like). Such wiring enablesconveyance of the high speed data signals 40 between the PSE device 22and PDs, as well as power signals 42 from the PSE device 22 to the PDs.Further details will now be provided with reference to FIG. 2.

FIG. 2 shows particular details of the power delivery circuitry 32 ofthe PSE device 22. In FIG. 2, the power supply 50 is represented assource V_supply and return V_return (e.g., −48 Volts).

Additionally, each physical port 34 includes four isolation transformers80. For example, the physical port 34(A) includes isolation transformers80(A)(1), 80(A)(2), 80(A)(3), 80(A)(4). Similarly, the physical port34(B) includes isolation transformers 80(B)(1), 80(B)(2), 80(B)(3),80(B)(4), and so on.

The primary side 82 of each isolation transformer 80 connects to thedata communications circuitry 30, and the secondary side 84 of eachisolation transformer 80 connects with the cabling 26 (also see FIG. 1),e.g., via an RJ45 connector. As a result, the data communicationscircuitry 30 (FIG. 1) is able to effectively send and receive datacommunications signals 40 through the physical ports 34 whilemaintaining DC electrical isolation with the secondary side 84 of thephysical ports 34.

The secondary sides 84 of the isolation transformers 80 have center taps86 which connect to either a particular power signal switch 54 or theV_return of the power supply 50 (also see FIG. 1). Specifically, inconnection with physical port 34(A), the center tap 86 of transformer80(A)(1) connects to the power signal switch 54(1)(A), the center tap 86of transformer 80(A)(2) connects to V_return, the center tap 86 oftransformer 80(A)(3) connects to the power signal switch 54(2)(A), andthe center tap 86 of transformer 80(A)(4) connects to V_return.Likewise, in connection with physical port 34(B), the center tap 86 oftransformer 80(B)(1) connects to the power signal switch 54(2)(B), thecenter tap 86 of transformer 80(B)(2) connects to V_return, the centertap 86 of transformer 80(B)(3) connects to the power signal switch54(1)(B), and the center tap 86 of transformer 80(B)(4) connects toV_return.

Each power signal switch 54 has a control terminal 90 which receives aspecific switch signal 62 from the power signal steering circuitry 56 tocontrol steering of power signals 42 from the power supply 50 to thephysical ports 34. In particular, control terminal 90(1)(A) receives aswitch signal 62(1)(A) which opens and closes the power signal switch54(1)(A). Control terminal 90(1)(B) receives a switch signal 62(1)(B)which opens and closes the power signal switch 54(1)(B). Controlterminal 90(2)(A) receives a switch signal 62(2)(A) which opens andcloses the power signal switch 54(2)(A). Control terminal 90(2)(B)receives a switch signal 62(2)(B) which opens and closes the powersignal switch 54(2)(B).

At this point, it should be understood that the power delivery circuitry32 of the PSE device 22 is capable of controlling connectivity betweenthe port power controllers 52 and the physical ports 34. For example, byopening and closing particular power signal switches 54, the powerdelivery circuitry 32 is capable of connecting one port power controller52 to a physical port 34 (e.g., to provide up to 30 Watts to a PD), ormultiple port power controllers 52 to the physical port 34 (e.g., toprovide up to 60 Watts to the PD).

For example, suppose that there are no external devices 24 in need ofinline power. In this situation, the power signal steering circuitry 56preferably connects each port power controller 52 to a particularphysical port 34 to allow circuitry within that port power controller 52to sense for the characteristic impedance of a PD (i.e., when someoneconnects a PD to the physical port 34). Here, the power signal steeringcircuitry 56 can provide a switch signal 62(1)(A) to the controlterminal 90(1)(A) to close the power signal switch 54(1)(A). At the sametime, the power signal steering circuitry 56 can provide a switch signal62(1)(B) to the control terminal 90(1)(B) to open the power signalswitch 54(1)(B) and thus disconnect the port power controller 52(1) fromthe physical port 34(B). As a result, the port power controller 52(1) isable to sense for the characteristic impedance of a PD throughtransformers 80(A)(1) and 80(A)(2) of the physical port 34(A).

Similarly, the power signal steering circuitry 56 can provide a switchsignal 62(2)(B) to the control terminal 90(2)(B) to close the powersignal switch 54(2)(B). At the same time, the power signal steeringcircuitry 56 can provide a switch signal 62(2)(A) to the controlterminal 90(2)(A) to open the power signal switch 54(2)(A) and thusdisconnect the port power controller 52(2) from the physical port 34(A).Thus, the port power controller 52(2) is able to sense for thecharacteristic impedance of a PD through transformers 80(B)(1) and80(B)(2) of the physical port 34(B).

In some arrangements, each power signal switch 54 is a MOSFET and thecontrol terminal 90 of that power signal switch 54 is the gate of thatMOSFET. In these arrangements, the power signal steering circuitry 56preferably provides separate switch signals 62 to control each MOSFET.In certain arrangements, the switch signal 62 to close a MOSFET is alogically inverted form of the switch signal 62 to open another MOSFET.

It should be understood that since the port power controllers 52 havebeen activated (e.g., they are fully operational and connected to thepower supply 50), the port power controllers 52 are able to providepower signals 42 in response to PD discovery. In some arrangements, themaximum amount of inline power that can be supplied by each port powercontroller 52 is 30 Watts although the PSE device 22 is capable ofdelivering up to 60 Watts through a physical port 34 by switchingmultiple port power controllers 52 to the same physical port 34.

FIG. 3 shows a situation in which a PD 100 connects to physical port34(A), and in which there is no PD connected to physical port 34(B).Here, the power signal steering circuitry 56 provides a set of switchsignals 62 to the power signal switches 54 to create a first switchconfiguration (also see FIGS. 1 and 2) which enables the port powercontrollers 52 to sense for the presence of PDs through the physicalports 34. In particular, the power signal switch 54(1)(A) is closed, andthe power signal switch 54(1)(B) is opened. Accordingly, the port powercontroller 52(1) connects to the physical port 34(A) but is disconnectedfrom the physical port 34(B), i.e., the disconnected path 104 from thepower signal switch 54(1)(B) to the physical port 34(B) is shown as adashed line. Additionally, the power signal switch 54(2)(B) is closed,and the power signal switch 54(2)(A) is opened. Accordingly, the portpower controller 52(2) connects to the physical port 34(B) but isdisconnected from the physical port 34(A), i.e., the disconnected path106 from the power signal switch 54(2)(A) to the physical port 34(A) isshown as a dashed line.

In the situation of FIG. 3, the port power controller 52(1) detects thepresence of the characteristic impedance through the closed power signalswitch 54(1)(A), and then provides a power signal 42 to provide inlinepower through the closed power signal switch 54(1)(A) and physical port34(A). As a result, the port power controller 52(1) delivers inlinepower through the physical port 34(A) and two twisted pairs 112 of thecabling 26(A) (i.e., two pair power, also see the transformers 80(A)(1),80(A)(2) of FIG. 2). However, as shown by further dashed lines, noinline power is provided through the other two twisted pairs 114 of thecabling 26(A) (i.e., also see the transformers 80(A)(3), 80(A)(4) ofFIG. 2). Nevertheless, data communications signals 40 are capable ofbeing exchanged through both twisted pair sets 112, 114 (i.e., all fourtransformers 80 of the physical port 34(A), see FIG. 2).

Now suppose that the PD 100 indicates that it can receive more than themaximum amount of inline power that can be supplied by the port powercontroller 52(1) (e.g., during classification or power renegotiation).If the port power controller 52(2) is active (e.g., able to sense) butnot currently delivering inline power through any physical port 34, thepower signal steering circuitry 56 (FIG. 1) is capable of directing apower signal 42 from the port power controller 52(2) to the physicalport 34(A) for four pair power delivery (see the feedback and controlsignals 64 in FIGS. 1 and 2).

FIG. 4 shows a second switch configuration created by the power signalsteering circuitry 56 (FIGS. 1 and 2) for four pair power delivery.Here, the power signal switches 54(1)(A) and 54(2(A) are closed, and thepower signal switches 54(1)(B) and 54(2(B) are opened. Accordingly, theport power controllers 52(1), 52(2) connect to the physical port 34(A).However, as shown by dashed lines, the port power controllers 52(1),52(2) are disconnected from the physical port 34(B). The port powercontrollers 52(2) are able to provide respective power signals 42 viaindividual discovery or by discovery by one of the port powercontrollers 52 and coordination via the power signal steering circuitry56. As a result, the port power controller 52(1) provides inline powerto the PD 100 through the physical port 34(A) and the two twisted pairs112 of the cabling 26(A), and the port power controller 52(2) providesinline power to the PD 100 through the physical port 34(A) and the twotwisted pairs 114 of the cabling 26(A).

Again, data communications signals 40 are capable of being exchangedthrough both twisted pair sets 112, 114 (i.e., all four transformers 80of the physical port 34(A), see FIG. 2) while the PSE device 22 deliversfour pair power to the PD 100. Moreover, although there is no inlinepower delivery through the physical port 34(B), data communicationssignals 40 are capable of being exchanged through the physical port34(B) with an non-PD style device or a device with external powernevertheless (also see the external device 24(B) in FIG. 1). Such asituation is makes efficient use of the resources of the power deliverycircuitry 32. In particular, there is no need to over provision thepower delivery circuitry 32 with multiple port power controller 52(1)exclusively dedicated to each physical port 34(B).

FIG. 5 shows a third switch configuration created by the power signalsteering circuitry 56 (FIGS. 1 and 2) in order to demonstrate the inlinepower distribution flexibility provided by the power delivery circuitry32. Suppose that a PD 100 connects to the physical port 34(B). Such asituation may occur after the configurations of FIGS. 3 and 4.

As shown in FIG. 5, the power signal steering circuitry 56 (FIGS. 1 and2) provides switch signals 62 to the power signal switches 54 to closepower signal switches 54(1)(B) and 54(2)(B), and simultaneously openpower signal switches 54(1)(A) and 54(2)(A) as shown by the dashedlines. As a result, the same port power controllers 52(1), 52(2) in theearlier-mentioned switch configurations of FIGS. 3 and 4 deliver inlinepower through the physical port 34(B) and the two twisted pair sets 112,114 of the cabling 26(B) (i.e., four pair power).

It should be understood that the various switch configurations describedin connection with FIGS. 3 through 5, and others (e.g., two pair powerthrough physical port 34(B), two pair power through both physical ports34(A), 34(B), and so on) are attainable via operation of the switches54. Such switch configurations alleviate the need to over provision thePSE device 22 with port power controllers 52 which are exclusivelydedicated to particular physical ports 34. Further details will now beprovided with reference to FIG. 6.

FIG. 6 shows a flowchart of a procedure 200 which is performed by thePSE device 22 of the electronic environment 20 (FIG. 1). In step 202,the PSE device 22 activates a set of port power controllers 52 whereeach port power controller 52 is constructed and arranged to deliverpower to a device through at most one physical port 34 at a time. Suchactivation may occur as soon as the PSE device 22 is turned on. At thispoint, the power signal steering circuitry 56 opens and closes certainswitches 54 so that each port power controller 52 is able to sense forthe presence of a PD through a particular physical port 34. For example,port power controller 52(1) senses through physical port 34(A), and portpower controller 52(2) senses through physical port 34(B).

In step 204, the PSE device 22 performs a set of discovery operations todiscover PD presence through the physical ports 34. In particular, theport power controllers 52 sense through the physical ports 34 andprovide discovery data to the power signal steering circuitry 56 in theform of the PD discovery signals 60 (FIG. 1). IEEE 802.3af-2003 and IEEE802.3at-2009 define detection and classification protocols which aresuitable for use by the port power controllers 52.

In step 206, the PSE device 22 steers power signals 42 appropriatelyamong the physical ports 34. In particular, the power signal steeringcircuitry 56 provides, based on the discovery data provided by the setof discovery operations, switching signals 62 to switches 54. As aresult, the switches 54 are able to direct delivery of inline powerthrough the physical ports 34 in an efficient and effective manner.

While various embodiments of the invention have been particularly shownand described, it will be understood by those skilled in the art thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the invention as defined by theappended claims.

For example, FIG. 1 shows the PSE device 22 as having two port powercontrollers 52 couple to each physical port 34. In other arrangements,more than two port power controllers 52 couple to each physical port 34.In these arrangements, additional switches 54 reside between the portpower controllers 52 and the physical ports 34 to control andconnectivity and steering of power signals 42 from the port powercontrollers 52 to the physical ports 34.

In some arrangements, the PSE device 22 includes some physical ports 34which are provisioned to provide either 4-pair power or 2-pair power,and other physical ports 34 which are simply provisioned to provide2-pair power. For example, suppose that a 48 port switch has two rows ofphysical ports 34, with each physical port 34 having a path to arespective port power controller 52. The switches 54 can be arranged sothat the first 24 physical ports 34 (e.g., a row including port #1through port #24) are capable of providing up to 4-pair power while thelast 24 physical ports 34 (e.g., another row including port #25 throughport #48) is merely capable of providing 2-pair power. Such aconfiguration provides enhanced user friendliness in that users canobtain 2-pair power or 4-pair power using physical ports 34 from left toright (e.g., the row of port #1 through port #24).

During operation, if the first 24 physical ports 34 currently provide4-pair power, the last 24 ports would not provide PoE. In thissituation, port #1 connects to the port power controller 52 for port #1as well as the port power controller 52 for port #48. As a result, port#48 no longer has a connection to its respective power controller 52,but would still be capable of operating as an Ethernet port. Othercombinations are available as well.

Additionally, it should be understood that the above-described circuitryis flexible in terms of when and how the switches 54 are turned on andoff. In some arrangements, once detection/classification passes on aparticular port 34 and the power signal steering circuitry 56 hasdetermined the appropriate 4-pair/2-pair power delivery situation forthe electronic environment 20 based on all available data, the powersignal steering circuitry 56 opens and closes the appropriate switches54 to route power to the proper port or ports 34.

Furthermore, it should be understood that it is possible to integrateone or more of the above-described components of the PSE device 22 in acommon package or PoE chip. In some arrangements, the switches 54 alongwith the port power controllers 52 reside in the same integrated circuitdevice.

What is claimed is:
 1. A method, comprising: performing, by controlcircuitry, a set of discovery operations to discover device presence,the set of discovery operations providing discovery data indicatingwhether an external powered device (PD) connects to a particular port ofa set of ports; outputting, by the control circuitry, a first switchingsignal to a first switch based on the discovery data, the first switchbeing disposed between a first power controller and the particular port;and outputting, by the control circuitry, a second switching signal to asecond switch based on the discovery data, the second switch beingdisposed between a second power controller and the particular port, thefirst power controller and the second power controller being configuredto only use the particular port at a time, wherein the first powercontroller and the second power controller each configured to operate inat least one of a discovery mode to periodically sense for a presence ofthe external PD or a power mode to perform a periodic power negotiationwith the external PD and to determine an amount of power provided byeach of the first and second power controllers to the external PDthrough the particular port based on the periodic power negotiation. 2.A method as in claim 1, further comprising: while outputting the firstswitching signal to the first switch and the second switching signal tothe second switch, sending data to the external PD and receiving datafrom the external PD through the port.
 3. A method as in claim 2 whereinoutputting the first switching signal includes providing the firstswitching signal to control opening and closing of the first switch; andwherein outputting the second switching signal includes providing thesecond switching signal to control opening and closing of the secondswitch independently of opening and closing of the first switch.
 4. Amethod as in claim 3 wherein providing the first switching signal tocontrol opening and closing of the first switch includes closing thefirst switch; wherein providing the first switching signal to controlopening and closing of the second switch includes closing the secondswitch; and wherein the first power controller and the second powercontroller concurrently deliver power to the external PD through theport while the first switch and the second switch are both closed.
 5. Amethod as in claim 4 wherein closing the first switch includes providinga first direct current signal to the external PD from the first powercontroller through a first set of conductors of the port; and whereinclosing the second switch includes providing a second direct currentsignal to the external PD from the second power controller through asecond set of conductors of the port.
 6. A method as in claim 3 whereinproviding the first switching signal to control opening and closing ofthe first switch includes closing the first switch; wherein providingthe first switching signal to control opening and closing of the secondswitch includes opening the second switch; wherein the first powercontroller delivers power to the external PD through the port while thefirst switch is closed; and wherein the second power controller does notdeliver power to the external PD through the port while the secondswitch is open.
 7. A method as in claim 6 wherein closing the firstswitch includes providing a first direct current signal to the externalPD from the first power controller through a first set of conductors ofthe port; and wherein opening the second switch includes preventing asecond direct current signal from being conveyed to the external PD fromthe second power controller through a second set of conductors of theport.
 8. A method as in claim 6, further comprising: outputting, by thecontrol circuitry, another switching signal to another switch, the otherswitch being disposed between the first power controller and anotherport.
 9. A method as in claim 8 wherein outputting the other switchingsignal includes opening the other switch to prevent the first directcurrent signal from being conveyed to another external PD from the firstpower controller through the other port.
 10. A method as in claim 1,further comprising: disconnecting all ports from the set of ports exceptthe particular port during the time when the first power controller andthe second power controller use the particular port.
 11. A method as inclaim 10 wherein outputting the other switching signal includes closingthe other switch to provide the second direct current signal to anotherexternal PD from the second power controller through the other port. 12.A method as in claim 1 wherein each power controller of the first andsecond power controllers has a maximum power capacity to power at mostone external PD at a time.
 13. An apparatus, comprising: a set ofphysical ports; a first power controller; a first switch disposedbetween the first power controller and a particular physical port of theset of physical ports; a second power controller, the first powercontroller and the second power controller each configured to operate inat least one of a discovery mode to periodically sense for a presence ofan external powered device (PD) or a power mode to determine perform aperiodic power negotiation with the external PD, the first powercontroller and the second power controller being configured to only usethe particular physical port at a time; a second switch disposed betweenthe second power controller and the particular physical port of the setof physical ports; and control circuitry coupled to the set of physicalports, the first switch and the second switch, the control circuitrybeing constructed and arranged to: perform a set of discovery operationsto discover device presence, the set of discovery operations providingdiscovery data indicating whether the external PD connects to theparticular physical port, output a first switching signal to the firstswitch based on the discovery data, and output a second switching signalto the second switch based on the discovery data, operation of the firstand second switches controlling an amount of power provided by each ofthe first and second power controllers to the external PD through theparticular physical port based on the periodic power negotiation.
 14. Anapparatus as in claim 13, further comprising: data communicationscircuitry coupled to the set of physical ports, the data communicationscircuitry being constructed and arranged to send data to the external PDand receive data from the external PD through the particular physicalport while the control circuitry outputs the first switching signal tothe first switch and the second switching signal to the second switch.15. An apparatus as in claim 14 wherein the control circuitry, whenoutputting the first switching signal, is constructed and arranged toprovide the first switching signal to control opening and closing of thefirst switch; and wherein the control circuitry, outputting the secondswitching signal, is constructed and arranged to provide the secondswitching signal to control opening and closing of the second switchindependently of opening and closing of the first switch.
 16. A computerprogram product having a non-transitory computer readable medium whichstores a set of instructions to control power delivery through a port,the set of instructions, when carried out by computerized circuitry,causing the computerized circuitry to perform a method of: performing aset of discovery operations to discover device presence, the set ofdiscovery operations providing discovery data indicating whether anexternal powered device (PD) connects to a particular port of a set ofports; outputting a first switching signal to a first switch based onthe discovery data, the first switch being disposed between a firstpower controller and the particular port; and outputting a secondswitching signal to a second switch based on the discovery data, thesecond switch being disposed between a second power controller and theparticular port, the first power controller and the second powercontroller being configured to only use the articular port at a time,wherein the first power controller and the second power controller eachconfigured to operate in at least one of a discovery mode toperiodically sense for a presence of the external PD or a power mode toperform a periodic power negotiation with the external PD and todetermine an amount of power provided by each of the first and secondpower controllers to the external PD through the particular port basedon the periodic power negotiation.
 17. A computer program product as inclaim 16 wherein the method further comprises: while outputting thefirst switching signal to the first switch and the second switchingsignal to the second switch, sending data to the external PD andreceiving data from the external PD through the port.
 18. A computerprogram product as in claim 17 wherein outputting the first switchingsignal includes providing the first switching signal to control openingand closing of the first switch; and wherein outputting the secondswitching signal includes providing the second switching signal tocontrol opening and closing of the second switch independently ofopening and closing of the first switch.